Abstract: 
Organic materials are promising for flexible and semi-transparent photodetectors. Two classes of organic photodetectors that have been developed are photodiodes and phototransistors. Photodiodes generate linear but weak signal upon incoming light, while phototransistors can achieve high gain but sub-linear photoresponse. This talk discusses a new device concept of organic dual-gate phototransistor that combines the operation of photodiodes and phototransistors to simultaneously enable high-gain and linear photoresponse without requiring external circuitry.  During dual-gate operation, the presence of both n- and p-type channels enables both photogenerated electrons and holes to efficiently separate and transport in the same semiconducting layer. This operation enables effective control of trap carrier density that leads to linear photoresponse with high photoconductive gain and a significant reduction of electrical noise. The use of organic dual-gate phototransistors for high-performance imaging and recent advances in non-fullerene organic photodiodes will be discussed.

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Biography: 
Philip Chow received his Ph.D. degree from the University of Cambridge in 2016 for his studies of charge dynamics in organic solar cells with Prof Richard Friend. After his Ph.D. he was awarded a JPSP Overseas Research Fellowship to work with Prof Takao Someya at the University of Tokyo, where he focused on developing organic photodetectors for imaging applications. He joined HKUST as a Research Assistant Professor in 2017, and his current research interests include non-fullerene organic solar cells and optoelectronic devices.